This invention relates to an increased tape capacity VCR tape cassette for use in an unmodified, conventional front loading VHS VCR recorder.
Conventional commercially available VCR tape cassettes generally have a recording time of up to four hours. The tapes are recorded on at a rate of twenty-five frames per second. In order to extend the recording times of these tapes time lapse technology may be employed to decrease the number of frames recorded per second. This reduction in the frame recording rate results a slow motion effect in the recording when played back.
In the security industry surveillance cameras are widely used to monitor security sensitive areas and in many security installations are connected to video tape recording machines for the recordal of activity in that area. In this application, although the time lapse recording increase the recording tape cassette change time, the slow motion effect produced by the tape could be detrimental to the accurate identification of people and/or events projected from the recorded tape.
An increased capacity VCR tape cassette for use with a front loading VHS VCR recorder according to the invention comprises a forward housing section which conforms to a conventional, i.e., standard, VCR tape cassette in which the tape spools are replaced by drive wheels which are adapted for releasable engagement with the recorder tape drive spindles, a rear tape section which includes a pair of rotatable tape reels, a bridge section which defines a passage which extends from an upper level of the rear wall of the forward housing section to the rear tape section which, in use, is located on the outside of a cassette opening to the recorder, a significantly longer than conventional recording tape which is wound on the two tape reels and passes from a first tape reel through the bridge passage into the forward cassette section to be recorded on and from the cassette section backthrough the bridge passage and onto the second tape reel, and drive means which extend from the forward cassette section drive wheels through the bridge passage and to the tape reels in the rear tape section of the cassette housing.
The passage through the bridge section of the cassette may include a throat which has a vertical dimension which is less than the width of the recording tape with the tape in its passage through the bridge section of the cassette being partially twisted from the orientation in which it is situated on the drive wheels and reels of the cassette to permit its passage through the bridge.
The upper surface of the rear tape section may be parallel to and situated above the upper surface of the forward housing section of the cassette and the bridge section includes a floor which is parallel to the upper surfaces of the forward and rear housing sections and which extends from a position on the rear wall of the forward housing section slightly below the upper surface of the forward housing section to the rear tape section and a cover piece which extends from the upper surface of the forward housing section to the rear tape section to define between it and the bridge section floor the bridge passage. Preferably, the bridge section extends over the width of the cassette and the bridge cover piece is upwardly inclined from the upper surface of the forward housing section to the rear tape section with the cover comprising a first flap which is hingedly attached and upwardly biased to the forward housing section with the width of the flap being such that its free edge parallel to the hinge, when the flap is pressed downwardly against its bias, is situated, on full insertion of the cassette into the recorder opening, on the outside of the opening and a second flap which is hingedly connected to the rear tape section with its edge portion, parallel to its hinge, bearing on the upper surface of the first cover flap.
In one form of the invention the tape reels in the rear tape section of the cassette housing are arranged in a side by side relationship in a common plane and the drive means may be endless belts which rotatably connect each of the drive wheels to a tape reel in a suitable drive ratio which will cater for the larger than normal tape reel diameters.
The tape reels may be floating reels the spindles of which are each movably engaged with a transverse guide track on the base of the rear tape section of the housing.
In another form of the invention the tape reels in the rear tape section of the housing are located one on the other and are independently rotatable on a common spindle. Conveniently, the tape reels are spools with the periphery of adjacent flanges of each of the spools being gear toothed and the drive means could be a gear train between each of the spool flanges and a gear on a drive wheel in the forward housing section of the cassette.
The drive means may, however, be endless belts which rotatably connect each of the drive wheels to a tape reel in a suitable ratio which will cater for the larger than normal tape reel diameters in use.
The drive belts in both forms of the invention have a cross-sectional height of between 1 mm and 2 mm, a toothed drive surface and are steel strand reinforced.